Described below is a method for producing a layer on a substrate. According to this method, a coating material which contains a solvent or dispersion medium, chemical precursors of a ceramic and absorber particles for an energy radiation is applied onto the substrate. The substrate provided with the coating material is then subjected to a heat treatment in which the solvent or dispersion medium is evaporated and the chemical precursors are converted into the ceramic so as to form the layer, the heat treatment including input of an electromagnetic energy radiation which is converted into heat by the absorber particles. The absorber particles therefore are formed of a material which makes it possible to absorb the energy radiation. The energy radiation must provide an energy which can be absorbed by particular absorber materials and be appropriately selected to suit the absorber particles used. Electromagnetic radiation is in particular used as the energy radiation and a wealth of materials are available for the selection of the material of the absorber particles (further details on this below), so that a material which suits the layer system to be produced can be selected as a function of the application.
The method of producing ceramic layers from chemical precursors of the ceramic is known per se. For example, such a method is described in WO 00/00660 A. The chemical precursors of the ceramic are materials which do not themselves belong to the material group of ceramics, but can be dissolved in solvents or dispersed in dispersion media. In this way, a liquid or paste is obtained which can be applied onto the substrate to be coated. A subsequent heat treatment is used first to evaporate the solvent or dispersion medium, so that the layer can solidify. A subsequent sintering treatment leads to crosslinking of the precursors to form the desired ceramic (pyrolysis). By applying a plurality of coats with different compositions, so-called multilayer or gradient layers, in which the layer composition changes continuously or stepwise, can also be produced by the method.
The input of heat during the heat treatment is typically carried out in an oven in which the substrate with the applied layer is heated to the desired temperature. According to DE 10 2007 026 626 B3, however, it is described that input of heat can also be carried out in a controlled way in that, for example, particles of a UV light absorber such as titanium oxide or zinc oxide can be incorporated into the layer. The heat treatment can then be carried out, or at least assisted, by UV light irradiation.